432 EFFECTS OF AQUEDUCTS AND CAI^ALS. 



bankmentSj and the like, divert water from its natural channels, 

 and efiect its distribution and ultimate discharge. The collecting 

 of the waters of a considerable district into reservoirs, to be 

 thence carried off by means of aqueducts — as, for example, in the 

 forest of Belgrade, near Constantinople — deprives the grounds, 

 originally watered by the springs and rivulets, of the necessary 

 moisture and reduces them to barrenness.* Similar effects must 

 have followed from the construction of the numerous aqueducts 

 which supphed ancient Rome with such a profuse abundance of 

 water, f On the other hand, the filtration of water through the banks 

 or walls of an aqueduct carried upon a high level across low ground, 

 often injures the adjacent soil, and is prejudicial to the health of 

 the neighboring population ; and it has been observed in Switzer- 

 land and elsewhere, that fevers have been produced by the stag- 

 nation of the water in excavations from which earth had been 

 taken to form embankments for railways. 



If we consider only the iafluence of physical improvements 

 on civilized life, we shall perhaps ascribe to navigable canals a 

 higher importance, or at least a more diversified influence, than 

 to aqueducts or to any other works of man designed to control 

 the waters of the earth, and to affect their distribution. They 

 bind distant regions together by social ties, through the agency 

 of the commerce they promote ; they facilitate the transporta- 

 tion of mihtary stores and engines, and of other heavy material 

 connected with the discharge of the functions of government ; 

 they encourage industry by giving marketable value to raw ma- 



river inundations in England is, with great probability, now ascribed to exces- 

 sive draining of the superficial strata of the soil. 



See also Asbjornsen, Torv og Torvdrift, p. 31. 



* See the very interesting paper referred to in note to p. 339, ante, on the 

 Water-Supply of Constantinople, by Mr. Homes, of the New York State 

 Library, in the Albany Argus of June 6, 1872. The system of aqueducts for 

 the supply of water to that city was commenced by Constantine, and the great 

 aqueduct, frequently ascribed to Justinian, which is 840 feet long and 113 

 feet high, is believed to have been constructed during the reign of the former 

 emperor. 



f The unhealthiness of the Roman Campagna is ascribed, by many mediaeval 

 as well as later writers, to the escape of water from the ancient aqueducts 

 which had fallen out of repair from neglect, or been broken down by enemies 

 in the sieges of Rome. 



